Thyroid Cancer

Definition

Thyroid cancer indicates the presence of a cancerous tumor in the thyroid gland, which is located just below the Adam's apple and is in charge of the regulation of blood pressure, heartbeat rate, temperature and weight, through the hormones that it produces.

Thyroid cancer is a less common type of cancer. However, its rate is increasing due to the improvement of technology that allows physicians to detect small cancers that were not previously diagnosed due to lack of means.

Work Group:

Prepared by: Scientific Section

Symptoms, Causes

Symptoms:

It is not likely for patients of thyroid cancer to experience any symptoms in its early stage, though as the disease progresses, the following might appear:

A lump on the neck felt under the skin

Changes in the voice (increased hoarseness)

Swallowing difficulties

Neck and throat pain

Swelling of neck lymph nodes

Medical care should be sought when noticing the above mentioned symptoms, but due to the infrequency of thyroid cancer, physicians tend to investigate other probable causes first, which may result in similar symptoms.

Causes:

Thyroid cancer develops when a genetic mutation occurs in the cells of the gland, the cause of which is yet unknown. Thus, defected cells start multiplying at a high rate and in contrast to normal cells, these cancerous cells don’t die, accumulating and forming a tumor; they may even spread and infect other tissues.

TYPES OF THYROID CANCER:Treatment and prognosis are determined according to the type of thyroid cancer. Some of these types are:

Papillary Thyroid Cancer:
The papillary type of thyroid cancer is the most common, making up about 80% of all thyroid cancer diagnoses. Papillary thyroid cancer can occur at any age, but is most commonly diagnosed in people ages 30 to 50.

Follicular Thyroid Cancer:
This type is more common in people above the age of 50 and also includes Hurthle cell cancer.

Medullary Thyroid Cancer:
Though most cases are sporadic, which means that they aren’t associated with inherited genetic syndromes, some are not sporadic and include tumors that infect other glands as well.

Anaplastic Thyroid Cancer:
This type is more common in people above the age of 60. It is a very uncommon, hard to treat and aggressive type of cancer.

Thyroid Lymphoma:
It is more common in people above the age of 70. It is a very rare type of cancer that begins in the immune system cells that are located in the thyroid.

Thyroid cancer risks are elevated due to the following factors:

Exposure to High Levels of Radiation:
This could be due to medical radiation treatment close to the thyroid gland or nuclear dust resulting from accidents or weapon testing.

Personal or Family History of Goiter:
This condition is the enlargement of the thyroid, but is noncancerous.

Complications

Complications:

Recurring thyroid cancer:
Even if treated by complete removal of the thyroid, cancer may return after decades, due to the microscopic cancer cells that already have spread out of the thyroid before its removal. Recurrence is most common in the:

Neck lymph nodes

Thyroid tissues that were not completely removed

Other organs, usually bones and lungs

To monitor recurrence, periodic blood tests are recommended along with thyroid scans.

Treatments:

Depending on the type and stage of the disease and the patient’s overall health and preferences, the course of treatment is determined.

SURGERY:
Surgery is a common form of treatment, in which partial or complete surgical removal of the thyroid gland is carried out. Some of the operations are listed below:

Thyroidectomy:
Also called a near-total thyroidectomy, in this surgery all or most of the thyroid is removed, except small rims around the parathyroid gland to avoid possible damage to it.

Removing lymph nodes in the neck:
This procedure is carried out in conjunction with thyroidectomy, in which the enlarged lymph nodes of the neck are removed to test them for cancer cells.

The operation is carried out through an incision at the base of the neck. Some risks of the surgery are bleeding and infection, damage to the parathyroid glands resulting in low calcium levels in the body, risk of accidental damage to the vocal cords resulting in vocal cord paralysis, hoarseness, soft voice or difficulty breathing.

THYROID HORMONE THERAPY:
After undergoing thyroid cancer surgery, thyroid hormone medications, such as levothyroxine, are prescribed to be taken throughout the rest of the patient’s life. These drugs supply the body with the hormones that the thyroid produces and they hinder the production of the thyroid-stimulating hormone (TSH) in the pituitary gland, whose production can also stimulate the cancer cells, if any are left behind.

The exact dose of these drugs is determined during a few months of hormone monitoring and blood tests.

RADIOACTIVE IODINE:
In this method, large doses of radioactive iodine are administered after thyroidectomy to eliminate any remaining thyroid tissues, whether healthy or cancerous, which were left behind after surgery due to their microscopic size. This method is also used to treat thyroid cancer that spreads throughout the body or that which recurs.

Radioactive iodine comes as a capsule or liquid and is administered orally; it specifically targets thyroid cells (healthy or cancerous), leaving the other cells of the body usually unharmed. Its side effects might include:

Pain where thyroid cancer cells have spread, such as the neck or chest

Dry mouth and eyes

Altered sense of taste or smell

Nausea

The body gets rid of most of the radioactive iodine through urine within a few days after its administration. During that period, the patient should be warned about avoiding contact with others, especially children and pregnant women, to protect them from radiation.

EXTERNAL RADIATION THERAPY:
Also called external beam radiation therapy, it is carried out with the help of a machine that aims a high energy beam precisely to the infected regions, over several weeks with five times a week and few minutes a day.

CHEMOTHERAPY:
This is a cancer treatment method, in which drugs are administered as an infusion through a vein, circulating the body and killing rapidly growing cells such as cancer cells.